The present invention relates to a fuel injection system for internal combustion engines having integral action regulation for influencing the fuel-air mixture supplied to the engine by means of an oxygen probe disposed in the exhaust gas conduit (.lambda. regulation).
When the mass ratio of the fuel-air mixture supplied to the internal combustion engine is to be influenced as a function of the composition of the exhaust gas, this is generally accomplished by means of an oxygen probe disposed in the exhaust gas flow of the engine and a regulating device which produces a corresponding increase or reduction in the respective quantity of fuel metered in proportion to the quantity of air in dependence on the output signal of the oxygen probe. It is known that this method of varying the fuel-air mixture can be implemented both in the case of engines equipped with carburetors and also in the case of engines equipped with fuel injection systems.
The regulating devices used to influence the mass ratio of the fuel-air mixture supplied to the engine are preferably integral action regulators and thus, when the exhaust gas composition deviates for a prolonged period from a nominal value, increasing correction of the mass ratio of the fuel-air mixture will take place.
In the case of the known fuel injection systems of this type regulation of the air number is provided at .lambda. = 1. The regulating range of the regulation devices used to influence the mass ratio of the fuel-air mixture must be kept relatively low to avoid interruptions in the performance of the engine at the requisite high regulating rates. If larger tolerances are produced in the engine or in the processing systems as a result of aging, or if marked changes are produced in the operating conditions of the engine, for example, as a result of variations in the temperature or pressure of the air drawn in, it is not possible to compensate for these variations in the case of the known fuel injection systems without considerable expenditure on construction.